Rock River Arms LR1297 LAR-PDS Carb Tri-Rail HG SA 223 Rem 16″” 30+1 6 Pos S RRA LAR-PDS Carbine with LAR-PDS Aluminum Tri-Rail Handguard is one of a new generation of firearms employing RRA s patent-pending Piston Driven System (PDS). Featuring a purpose designed bolt carrier, an adjustable gas piston and an over-the-barrel spring and guide rod arrangement, the RRA LAR-PDS is able to completely do away with the traditional recoil system associated with AR-style firearms, making for an extremely versatile weapon platform and allowing for a folding stock. The firearm measures 26″ with the stock folded!